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63.
The momentum distributions of He+ fragments from photodissociation of He+2 ions have been recorded in a crossed-beams experiment. The discrete values of the kinetic energy releases can be predicted from the vibrational spacings in the ground state of the primary ions. 相似文献
64.
P.G. Fournier G. Comtet R.W. Odom R. Locht J.G. Maas N.P.F.B. Van Asselt J. Los 《Chemical physics letters》1976,40(1):170-174
We have repeated the experiment on the accurate measurement of the kinetic energy released during the predissociation of HeH+ ions into the fragments H+ and He. This experiment was carried out on two machines specially designed for this purpose. The new results differ from those of the original experiment and agree now very well with the theoretical predictions. 相似文献
65.
66.
Renata Los Marta Wesoowska‐Trojanowska Anna Malm Monika M. Karpiska Joanna Matysiak Andrzej Niewiadomy Urszula Gaszcz 《Heteroatom Chemistry》2012,23(3):265-275
A new synthesis method of benzimidazoles, dihydroquinazolines, and other related compounds containing a 2,4‐dihydroxyphenyl moiety was elaborated. Their structures were identified from elemental, infrared, 1H NMR, 13C NMR, and mass spectra analyses. The minimal inhibitory concentration values of the compounds toward eight reference bacterial strains were determined by the two‐fold serial microdilution broth method. The compounds exhibited substantial inhibitory effects against the Gram‐positive strains tested contrary to Gram‐negative ones. The compounds of imidazopyridine, N‐methylbenzimidazole, and dihydroquinazoline structures exhibited the largest activity. The magnification of covering a two‐nitrogen atom heterocyclic ring fused to a benzene one decreases the biological effect. © 2012 Wiley Periodicals, Inc. Heteroatom Chem 23:265–275, 2012; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.21012 相似文献
67.
V. F. Los 《Theoretical and Mathematical Physics》2009,160(2):1124-1143
We develop a new method based on using a time-dependent operator (generally not a projection operator) converting a distribution
function (statistical operator) of a total system into the relevant form that allows deriving new exact nonlinear generalized
master equations (GMEs). The derived inhomogeneous nonlinear GME is a generalization of the linear Nakajima-Zwanzig GME and
can be viewed as an alternative to the BBGKY chain. It is suitable for obtaining both nonlinear and linear evolution equations.
As in the conventional linear GME, there is an inhomogeneous term comprising all multiparticle initial correlations. To include
the initial correlations into consideration, we convert the obtained inhomogeneous nonlinear GME into the homogenous form
by the previously suggested method. We use no conventional approximation like the random phase approximation (RPA) or the
Bogoliubov principle of weakening of initial correlations. The obtained exact homogeneous nonlinear GME describes all evolution
stages of the (sub)system of interest and treats initial correlations on an equal footing with collisions via the modified
memory kernel. As an application, we obtain a new homogeneous nonlinear equation retaining initial correlations for a one-particle
distribution function of the spatially inhomogeneous nonideal gas of classical particles. In contrast to existing approaches,
this equation holds for all time scales and takes the influence of pair collisions and initial correlations on the dissipative
and nondissipative characteristics of the system into account consistently with the adopted approximation (linear in the gas
density). We show that on the kinetic time scale, the time-reversible terms resulting from the initial correlations vanish
(if the particle dynamics are endowed with the mixing property) and this equation can be converted into the Vlasov-Landau
and Boltzmann equations without any additional commonly used approximations. The entire process of transition can thus be
followed from the initial reversible stage of the evolution to the irreversible kinetic stage. 相似文献
68.
L. Bongini F. Piazza L. Casetti P. De Los Rios 《The European physical journal. E, Soft matter》2010,33(1):89-96
In this paper we analyze the vibrational spectra of a large ensemble of non-homologous protein structures by means of a novel
tool, that we coin Hierarchical Network Model (HNM). Our coarse-grained scheme accounts for the intrinsic heterogeneity of
force constants displayed by protein arrangements and also incorporates side chain degrees of freedom. Our analysis shows
that vibrational entropy per unit residue correlates with the content of secondary structure. Furthermore, we assess the individual
contribution to vibrational entropy of the novel features of our scheme as compared with the predictions of state-of-the-art
network models. This analysis highlights the importance of properly accounting for the intrinsic hierarchy in force strengths
typical of the different atomic bonds that build up and stabilize protein scaffolds. Finally, we discuss possible implications
of our findings in the context of protein aggregation phenomena. 相似文献
69.
J. R. Martín de Los Santos R. Martínez-Herrero P. M. Mejías 《Optical and Quantum Electronics》1996,28(8):1021-1027
On the basis of the intensity moment formalism, within the thin-sheet approach, the beam width, the beam quality and the kurtosis parameter of a Gaussian beam propagating through active media are investigated. The analysis considers both the homogeneously and inhomogeneously broadened cases. The dependence of the above three parameters on the small-signal gain, saturation intensity and input beam size is studied. The validity of the thin-sheet approximation for the range of propagation distances and physical parameters of the system is also discussed. 相似文献
70.
The reflection of protons from a partially cesiated tungsten surface is studied in the energy domain between 100 and 2000 eV and in the angular domain between 75° and 85° with respect to the surface normal. The study is performed by measuring the angular and energy distribution of the scattered negative ions. The reflection can take place along two paths. One path is reflection from the cesium surface layer, the other one is reflection from the tungsten substrate. A dependence of the final charge state on the path is observed. It is inferred that this phenomenon is due to incomplete neutralization of the protons scattered from the cesium layer. The energy loss of the reflected ions cannot be accounted for by using only the binary collision model. Also the electronic stopping of the atoms by the metal electrons is shown to be an important energy loss mechanism. Total conversion measurements of H+ to H- combined with the measurements of the negatively charged fraction of the scattered particles, as reported in the proceeding paper, yield the particle reflection coefficient as a function of the angle of incidence. These reflection coefficients show that for angles of incidence less than 75° already more than 50% of the particles do not reflect from the surface. Total conversion efficiency measurements with H- ions as primary ions show that the influence of the initial charge state on the total conversion is very small. 相似文献